The invention relates to a switching arrangement for regulation of the fuel-air mixture delivered to an internal combustion engine by means of an oxygen-measuring sensor, disposed in the flow of exhaust gas of the internal combustion engine, which delivers an electric switching signal to the control unit of a fuel injection system as a function of the composition of the fuel-air mixture, whereby the fuel injection system is constituted by an air-measuring driveless injection system (i.e., not driven by an engine power take-off such as a drive belt) with continuous fuel flow supplied by an electric fuel pump, which system can be affected by a supplementary air valve and a warm-up control, and includes a timed valve (see, Bosch, Technical Instruction Gasoline Injection K-Jetronic, 1st issue, February, 1974).
A known switching device for regulation of the fuel-air mixture delivered by a fuel injection system of the K-Jetronic type in question, of an internal combustion engine, by means of an oxygen-measurement sensor disposed in the exhaust flow of the internal combustion engine has a main relay, and an rpm relay that is affected by the rpm of the engine. In this prior art arrangement, the control unit and the timed valve are associated with the main relay, and the electric fuel pump, the supplementary air valve and the warm-up control are associated with the rpm relay. As such, this arrangement has, in addition to the relatively high cost, a particular drawback because of the necessarily cumbersome design of the circuitry of the main relay and the rpm relay.
The present invention deals with the problem of simplifying a switching arrangement for regulation of the fuel-air mixture delivered by an air-measuring driveless injection system with continuous fuel flow, of an internal combustion engine, by means of an oxygen-measurement sensor disposed in the exhaust flow of the internal combustion engine.
According to a preferred embodiment of the invention, this problem is solved in that the switching arrangement has only a rpm relay, which is of a known type that can be influenced by the rpm of the internal combustion engine and which undertakes the control of the control unit and the timed valve in addition to its former control functions (fuel pump, supplementary air valve, warm-up control).
In particular, the advantages attained by the present invention are that, by elimination of the main relay, there is a cost-lowering simplification of the switching arrangement with an increase in reliability of operation.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with the present invention.